When two user equipment terminals (e.g., mobile communication devices) of a cellular network or other telecommunication system communicate with each other, their data path typically goes through the operator network. The data path through the network may include base stations and/or gateways. If the devices are in close proximity with each other, their data path may be routed locally through a local base station. In general, communications between a network node such as a base station and a wireless terminal is known as “WAN” or “Cellular communication”.
It is also possible for two user equipment terminals in close proximity to each other to establish a direct link without the need to go through a base station. Telecommunications systems may use or enable device-to-device (“D2D”) communication, in which two or more user equipment terminals directly communicate with one another. In D2D communication, voice and data traffic (referred to herein as “communication signals” or “communications”) from one user equipment terminal to one or more other user equipment terminals may not be communicated through a base station or other network control device of a telecommunication system. “Device-to-device (“D2D”) communication may also be known as “sidelink direct” communication (e.g., sidelink communication), or even as “sidelink”, “SL”, or “SLD” communication.
D2D or sidelink direct communication can be used in networks implemented according to any suitable telecommunications standard. A non-limiting example of such as standard is the 3rd Generation Partnership Project (“3GPP”) Long Term Evolution (“LTE”). The 3GPP standard is a collaboration agreement that aims to define globally applicable technical specifications and technical reports for third and fourth generation wireless communication systems. The 3GPP may define specifications for next generation mobile networks, systems, and devices.
The 3GPP LTE-A system has specified a feature that provides for the support of efficient communications of small data objects between Transmit and Receive devices. Such LTE-A communication of small data objects between Transmit and Receive devices is known as Machine Type Communications (MTC). In this case, the transmitting device may be an eNB and the receiving data may be a UE, or vice-versa.
The 3GPP LTE-A system has also specified a feature that provides for the support of direct communications between transmit and receive devices, known as Proximity Services (ProSe). Proximity services consists of two main elements: network assisted discovery of transmit and receive devices that are in close physical proximity and the facilitation of direct communication between such transmit and receive devices with, or without, supervision from the network. Direct communication means a radio connection is established between the transmit and the receive devices without transiting via the network. This direct communication protocol is also known as the aforementioned sidelink. In direct communication, the transmitting device may be a user equipment (UE) and the receiving data may also be a user equipment.
Currently 3GPP is specifying a new feature for Rel-14 that covers use cases and potential requirements for LTE support for vehicular communications services (represented by the term, Vehicle-to-Everything (V2X) Services). The feature is documented in the TR 22.885 on LTE Study on LTE Support for V2X Services. The documents provide definitions for the following terms:                Road Side Unit: An entity supporting V2I Service that can transmit to, and receive from a UE using V2I application. RSU is implemented in an eNB or a stationary UE.        V2I Service: A type of V2X Service, where one party is a UE and the other party is an RSU both using V2I application.        V2P Service: A type of V2X Service, where both parties of the communication are UEs using V2P application.        V2V Service: A type of V2X Service, where both parties of the communication are UEs using V2V application.        V2X Service: A type of communication service that involves a transmitting or receiving UE using V2V application via 3GPP transport. Based on the other party involved in the communication, it can be further divided into V2V Service, V2I Service, V2P Service, and V2N Service.        
The V2V service is intended to support use cases related to road safety. One such use case is known as collision avoidance. The collision avoidance use case provides that a first vehicle (equipped with a ProSe enabled UE that supports V2V services) may transmit from time-to-time or continuously information (e.g., a VDO transmission) about the vehicle including a vehicle unique identifier. In addition a second vehicle (also equipped with a ProSe enabled UE that support V2V services) may receive from time-to-time or continuously the VDO transmissions from the first vehicle. The second vehicle may analyze and compare the second vehicle's VDO to the VDO received from the first vehicle. The second vehicle may further determine if there is a probability that the two vehicles will occupy the same space at the same time in the near future.
What is needed are methods, apparatus, and/or techniques for controlling transmissions from mobile vehicles involved in vehicle (V2X) communications, such as for collision avoidance for example.